Mammography, including x-ray imaging and other imaging modalities, is widely used in detection and analysis of cysts, lesions, microcalcifications and other areas of interest within a patient's breast. Because of its proved effectiveness in early detection and diagnosis, including detection and diagnosis of non-palpable lesions, mammography continues to be recommended for many women. As a result, mammography equipment is available in many locations and such equipment, as well as clinicians and physicians experienced in using such equipment and analyzing the mammographic images, are typically kept busy meeting the demand for mammographic services.
Currently, most x-ray mammography systems are been film-based, although digital systems are gradually becoming more common. Physicians' preferences for film-based or digital systems depend on associated workflow processing as well as screening and diagnostic efficacy. During screening, common image projection views, such as the cranial caudal (CC) and medial lateral oblique (MLO) views are typically obtained for each patient. For example, such images may be obtained in connection with an annual screening process. Images for many patients may be acquired, for example, over the course of day. In the case of film-based mammography, the associated films may then be organized for review by a physician. In some cases, such review may involve comparing current films for a patient to films acquired on prior visits. If something suspicious is identified as a result of the screening process, a physician may acquire additional images from that patient, resulting in a further office visit by the patient.
Film-based mammography has certain perceived advantages. First, film-based mammography equipment is readily available. In addition, many physicians and clinicians are familiar with the equipment and the resulting images such that retraining is minimized. Moreover, physicians have significant flexibility in organizing films for display on a lightbox and such reviews can be accomplished efficiently.
More recently, digital mammography has been gaining acceptance. In digital mammography, images are acquired digitally and can be displayed on electronic monitors.
A number of advantages associated with digital imaging have been recognized. First, digital imaging provides near real-time images. In some cases, additional views may be acquired based on near real-time review of the digital images such that a return visit by the patient can be avoided. In addition, digital processing allows for image enhancement. In this regard, a physician may zoom in on an area of interest, adjust the image contrast or brightness or otherwise manipulate the image after acquisition. Moreover, it is sometimes possible to obtain improved diagnostic information by digital processing. For example, a digital image that is identified as being suspicious or is otherwise of interest can be exported to certain CAD systems that perform digital analyses. For example, such CAD systems may perform a pixel-by-pixel analysis of the digital image to identify areas of reduced intensity that may be missed upon review of the images using the naked eye. Such areas may indicate microcalcifications or other conditions of interest that the physician may desire to review more closely, such as by zooming in on that region of the image or otherwise enhancing the image.
Despite these advantages, certain perceived disadvantages have slowed the process of full digital acceptance. Some of the perceived disadvantages are specific to particular digital imaging equipment. In this regard, some current digital imaging systems do not provide a full field of view for a patient's breast. As a result, multiple images may be required for a screening analysis or the digital imaging system may be relegated to follow-up imaging of an area identified by film or other applications such as stereotactic localization. In addition, some current digital imaging systems provide a limited resolution that may be deemed insufficient for certain applications. However, full field, high-resolution digital imaging systems are now being marketed, including the SenoScan™ system of Fischer Imaging Corp. of Thornton, Colo.
Other perceived disadvantages relate to inefficiencies in the manner that digital imaging equipment is used. Many conventional digital mammography systems are stand alone units that include the patient imaging station or gantry (e.g., the x-ray tube, compression paddle, detector and the like), a processor executing image processing logic and a display terminal that may include oversized high resolution monitors. In these cases, a physician may review images at the image acquisition site. This may tie up the equipment when needed or require that the physician plan around a schedule for accessing the equipment.
Moreover, many physicians feel that using an electronic monitor to review images is slower than reviewing films. In the case of films, a physician may review a large quantity of films in one session. The films may be arranged in an order designated by the physician. When the films are thus properly prepared, an experienced physician may be able to adequately analyze certain images or sets of images in a matter of seconds, while devoting a larger time period to a subset of images requiring further analysis. In the digital context, significant time may be spent retrieving and arranging images. Even after an image is identified for review, significant time may be required to load and display the image due to the large amount of information contained in a high quality image. These operational difficulties have resulted in some degree of resistance to digital mammography in spite of the potential advantages as noted above.